U.S. patent application number 12/049117 was filed with the patent office on 2008-09-18 for cooling an electrical machine.
This patent application is currently assigned to DIRECT DRIVE SYSTEMS, INC.. Invention is credited to Cassandra Bailey, Paulo Guedes-Pinto, Daniel M. Saban.
Application Number | 20080224551 12/049117 |
Document ID | / |
Family ID | 39537506 |
Filed Date | 2008-09-18 |
United States Patent
Application |
20080224551 |
Kind Code |
A1 |
Saban; Daniel M. ; et
al. |
September 18, 2008 |
Cooling an Electrical Machine
Abstract
An electrical machine includes a stator and a rotor disposed in
a housing of the electrical machine. The stator includes windings
having a first set of end turns at a first end of the stator and
having a second set of end turns at a second, opposing end of the
stator. The stator has a substantially tubular shape and an
interior lateral surface. The rotor extends through the interior of
the stator. A flow inlet into a volume in the housing about the
first end turns is located radially outside of the interior lateral
surface of the stator. A flow outlet from the volume in the housing
about the first end turns is located radially outside of the
interior lateral surface. The inlet and the outlet are
cooperatively arranged to communicate a flow of fluid substantially
transverse across the first end of the stator.
Inventors: |
Saban; Daniel M.; (Corona,
CA) ; Bailey; Cassandra; (Anaheim, CA) ;
Guedes-Pinto; Paulo; (Brea, CA) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
DIRECT DRIVE SYSTEMS, INC.
Cerritos
CA
|
Family ID: |
39537506 |
Appl. No.: |
12/049117 |
Filed: |
March 14, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60895025 |
Mar 15, 2007 |
|
|
|
Current U.S.
Class: |
310/54 ;
165/104.33; 310/58; 310/59 |
Current CPC
Class: |
H02K 9/12 20130101; H02K
5/20 20130101 |
Class at
Publication: |
310/54 ; 310/58;
310/59; 165/104.33 |
International
Class: |
H02K 9/19 20060101
H02K009/19; F28D 15/00 20060101 F28D015/00 |
Claims
1. An electrical machine comprising: a stator disposed in a housing
of the electrical machine and comprising windings having a first
plurality of end turns at a first end of the stator and second
plurality of end turns at a second, opposing end of the stator, the
stator having a substantially tubular shape and an interior lateral
surface; a rotor extending through an interior of the stator; a
flow inlet into a volume in the housing about the first end turns,
the flow inlet located radially outside of the interior lateral
surface; and a flow outlet from the volume in the housing about the
first end turns, the flow outlet located radially outside of the
interior lateral surface, the inlet and the outlet cooperatively
arranged to communicate a flow of fluid substantially transverse
across the first end of the stator.
2. The electrical machine of claim 1, the flow outlet comprising a
first flow outlet, the flow inlet comprising a first flow inlet,
the volume comprising a first volume, the flow comprising a first
flow, further comprising: a second flow inlet into a second volume
about the second end turns, the second flow inlet located radially
outside of the interior lateral surface; and a second flow outlet
from the second volume about the second end turns, the flow outlet
located radially outside of the interior lateral surface, the
second inlet and the second outlet cooperatively arranged to
communicate the second flow substantially transverse across the
second end of the stator.
3. The electrical machine of claim 2, the first flow inlet and the
second flow inlet in fluid communication with a single source of
cooling fluid.
4. The electrical machine of claim 1, further comprising a
partition in the housing defining the volume, the flow outlet
comprising at least one port through the partition.
5. The electrical machine of claim 1, the flow inlet comprising a
first flow inlet, the electrical machine further comprising a
second flow inlet directing a second flow through a manifold
axially dividing a core of the stator to an air gap defined between
the interior lateral surface of the stator and an exterior lateral
surface of the rotor.
6. The electrical machine of claim 5, the second flow inlet
comprising a plurality of flow inlets at different azimuthal
locations around the stator.
7. The electrical machine of claim 5, the first flow inlet and the
second flow inlet in fluid communication with a single source of
cooling fluid.
8. The electrical machine of claim 5, the first flow inlet in fluid
communication with a first cooling source, the second flow inlet in
fluid communication with a second cooling source.
9. The electrical machine of claim 5, the second flow inlet
directing flow to an axial center of the air gap, the air gap
extending in an axial direction to the volume about the first end
turns.
10. The electrical machine of claim 1, further comprising at least
one cooling jacket around an exterior of the stator, the at least
one cooling jacket configured to circulate liquid cooling fluid
circumferentially around the stator to cool the stator.
11. The electrical machine of claim 10, the at least one liquid
cooling jacket defining a plurality of serpentine flow paths, each
serpentine flow path to circulate the liquid cooling fluid around a
different axial section of the stator to cool the axial section of
the stator.
12. The electrical machine of claim 10, the at least one liquid
cooling jacket separable from the housing and separable from the
stator.
13. A method of cooling an electrical machine, the method
comprising: in a housing of the electrical machine, receiving
cooling fluid into a volume about a first end of a stator disposed
within the housing, the stator comprising windings having a first
plurality of end turns at the first end of the stator and a second
plurality of end turns at a second, opposing end of the stator, the
stator having a substantially tubular shape and an interior lateral
surface, the flow received into the volume from radially outside of
the interior lateral surface; communicating the cooling fluid
substantially transverse across the first end of the stator; and
collecting the cooling fluid from the volume from radially outside
of the interior lateral surface.
14. The method of claim 13, the volume comprising a first volume,
the cooling fluid comprising a first flow of cooling fluid, the
method further comprising: receiving a second flow of cooling fluid
from outside of the interior lateral surface into a second volume
about the second end of the stator; communicating the second flow
of cooling fluid substantially transverse across the second end of
the stator; and collecting the second flow of cooling fluid from
the second volume from outside of the interior lateral surface.
15. The method of claim 14, wherein receiving the first flow of
cooling fluid comprises receiving the first flow of cooling fluid
from a first cooling fluid source, and receiving the second flow of
cooling fluid comprises receiving the second flow of cooling fluid
from the first cooling fluid source.
16. The method of claim 14, wherein receiving the first flow of
cooling fluid comprises receiving the first flow of cooling fluid
from a first cooling fluid source, and receiving the second flow of
cooling fluid comprises receiving the second flow of cooling fluid
from a second cooling fluid source.
17. The method of claim 13, the cooling fluid comprising a first
flow of cooling fluid, the method further comprising directing a
second flow of cooling fluid from a plurality of different
azimuthal locations around the exterior of the stator through a gap
axially dividing a core of the stator to an air gap defined between
the interior lateral surface of the stator and an exterior lateral
surface of a rotor extending through the stator.
18. An electrical machine comprising: a substantially cylindrical
stator disposed in a housing of the electrical machine and
comprising windings having a first plurality of end turns at a
first end of the stator and second plurality of end turns at a
second, opposing end of the stator; a rotor extending
longitudinally through an interior of the stator; a plurality of
first inlets at multiple locations distributed azimuthally around
an exterior of the stator directing flow through a gap axially
dividing a core of the stator to an air gap defined between the
stator and the rotor, the air gap extending through the interior of
the stator from a volume in the housing external to the stator
about the first end turns to a volume in the housing external to
the stator about the second end turns.
19. The electrical machine of claim 18, further comprising: a
second inlet into the volume in the housing external to the stator
about the first end turns; and a first outlet from the volume in
the housing external to the stator about the first end turns, the
second inlet and the first outlet cooperatively arranged to
displace cooling fluid across an outer diameter of the first end of
the stator while the fluid is in the volume external to the stator
about the first end turns.
20. The electrical machine of claim 19, further comprising: a third
inlet into the volume in the housing external to the stator about
the second end turns; and a second outlet from the volume in the
housing external to the stator about the second end turns, the
third inlet and the second outlet cooperatively arranged to
displace cooling fluid across an outer diameter of the second end
of the stator while the fluid is in the volume external to the
stator about the second end turns.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to and claims the benefit of
co-pending U.S. Provisional Patent Application 60/895,025 entitled
"High-Speed, Sleeved Rotor for Permanent Magnet Electric Machine"
by Saban, et al., filed Mar. 15, 2007, which is incorporated herein
by reference.
BACKGROUND
[0002] This description relates to motoring and/or generating
systems.
[0003] Some power systems may convert mechanical energy into
electrical energy and/or convert electrical energy into mechanical
energy. For example, generating systems can include a prime mover
and an electrical machine that generates electricity by converting
mechanical energy into electricity. Similarly, motoring systems can
include a mechanical load coupled to an electric machine that can
convert electricity into movement. In some systems, the electric
machine can be operated to generate electricity and convert
electricity into movement. Converting energy between the mechanical
and electrical domain generates heat, as does movement of the
mechanical components of the electric machine.
SUMMARY
[0004] An electrical machine includes a stator. Cooling fluid is
communicated through a volume external to the stator substantially
transverse across one or both ends of the stator, and/or cooling
fluid is communicated through a volume internal to the stator in an
axial direction toward one or both ends of the stator.
[0005] In certain aspects, an electrical machine includes a stator
and a rotor disposed in a housing of the electrical machine. The
stator includes windings having a first set of end turns at a first
end of the stator and having a second set of end turns at a second,
opposing end of the stator. The stator has a substantially tubular
shape and an interior lateral surface. The rotor extends through
the interior of the stator. A flow inlet into a volume in the
housing about the first end turns is located radially outside of
the interior lateral surface of the stator. A flow outlet from the
volume in the housing about the first end turns is located radially
outside of the interior lateral surface. The inlet and the outlet
are cooperatively arranged to communicate a flow of fluid
substantially transverse across the first end of the stator.
[0006] In certain aspects, an electrical machine includes a
substantially cylindrical stator and a rotor disposed in a housing
of the electrical machine. The stator includes windings having a
first set of end turns at a first end of the stator and second set
of end turns at a second, opposing end of the stator. The rotor
extends longitudinally through an interior of the stator. Multiple
first inlets are located at locations distributed azimuthally
around an exterior of the stator. The first inlets direct flow
through a gap axially dividing a core of the stator to an air gap
defined between the stator and the rotor. The air gap extends
through the interior of the stator from a volume in the housing
external to the stator about the first end turns to a volume in the
housing external to the stator about the second end turns.
[0007] In certain aspects, in a housing of an electrical machine,
cooling fluid is received into a volume about a first end of a
stator disposed within the housing. The stator includes windings
having a first set of end turns at the first end of the stator and
a second set of end turns at a second, opposing end of the stator.
The stator has a substantially tubular shape and an interior
lateral surface, and the flow is received into the volume from
radially outside of the interior lateral surface. The flow of
cooling fluid is communicated substantially transverse across the
first end of the stator. The cooling fluid is collected from the
volume from radially outside of the interior lateral surface.
[0008] Implementations can include one or more of the following
features. The flow outlet can be a first flow outlet, the flow
inlet can be a first flow inlet, the volume can be a first volume,
and the flow can be a first flow. The electrical machine can
include a second flow inlet into a second volume about the second
end turns. The second flow inlet can be located radially outside of
the interior lateral surface. The electrical machine can include a
second flow outlet from the second volume. The second flow outlet
can be located radially outside of the interior lateral surface.
The second inlet and the second outlet can be cooperatively
arranged to communicate the second flow substantially transverse
across the second end of the stator. The first flow inlet and the
second flow inlet can be in fluid communication with a single
source of cooling fluid. A partition in the housing can define the
volume about the first end turns, and the flow outlet can be
implemented as one or more ports through the partition. The
electrical machine can include a second flow inlet directing a
second flow through a manifold axially dividing a core of the
stator to an air gap defined between the interior lateral surface
of the stator and an exterior lateral surface of the rotor. The
second flow inlet can be multiple flow inlets at different
azimuthal locations around the stator. The first flow inlet and the
second flow inlet can be in fluid communication with a single
source of cooling fluid. The first flow inlet can be in fluid
communication with a first cooling source, and the second flow
inlet can be in fluid communication with a second cooling source.
The second flow inlet can direct flow to an axial center of the air
gap. The air gap can extend in an axial direction to the volume
about the first end turns. One or more cooling jackets around an
exterior of the stator can circulate liquid cooling fluid
circumferentially around the stator to cool the stator. The one or
more liquid cooling jackets can define a plurality of serpentine
flow paths, where each serpentine flow path circulates the liquid
cooling fluid around a different axial section of the stator to
cool the axial section of the stator. The liquid cooling jacket can
be separable from the housing and separable from the stator. The
first inlet and the first outlet can be cooperatively arranged to
displace cooling fluid across an outer diameter of the first end of
the stator while the fluid is in the volume external to the stator
about the first end turns.
[0009] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other features
will be apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0010] FIG. 1A is a cross-sectional view of an example electrical
machine and cooling system.
[0011] FIG. 1B is a cross-sectional view taken along line A-A in
FIG. 1A.
[0012] FIG. 2A is a cross-sectional view of an example electrical
machine and cooling system.
[0013] FIG. 2B is a cross-sectional view taken along line B-B in
FIG. 2A.
[0014] FIG. 3 is a flow chart illustrating an example process for
cooling an electric machine.
[0015] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0016] FIGS. 1 and 2 illustrate two example embodiments of an
electrical machine that includes a cooling system. FIG. 1A is a
cross-sectional view of an example electrical machine 100. FIG. 1B
is a cross-sectional side view of the electrical machine 100 taken
along line A-A in FIG. 1. FIG. 2A is a cross-sectional view of
another example electrical machine 200. FIG. 2B is a
cross-sectional side view of the electrical machine 200 taken along
line B-B in FIG. 2A.
[0017] The example electrical machine 100 (referred to
interchangeably hereinafter as "machines") includes a rotor 40
extending through the interior of a substantially cylindrical
stator 30, which resides in a housing 20. The stator 30 includes
multiple conductive windings 32 wound upon a laminated
ferromagnetic core of the stator 30. The windings 32 extend in an
axial direction between the two opposing ends of the stator 30. At
both ends of the stator 30, the windings 32 define multiple end
turns 34. The rotor 40 includes permanent magnets and is rotatable
within the stator 30. An outer diameter of the rotor 40 and an
inner diameter of the stator 30 define an air gap 60 between the
stator 30 and the rotor 40. The rotor 40 is supported by bearings
45. Some examples of bearings include magnetic bearings, magnetic
hybrid bearings, roller bearings, dynamic bearings, journal
bearings, thrust bearings, and other types of bearings. The rotor
40 may be supported by any combination of bearings or by bearings
of uniform type.
[0018] The electrical machine 100 can operate as a motor or a
generator. In the generator mode, rotation of the rotor 40 with
respect to the stator 30 induces an electromotive force across the
windings 32, thereby inducing a voltage across the windings 32,
which allows an electric current to flow when a circuit, as part of
an external system (unillustrated), is closed across the windings
32. The induced electric current can then be used to output
electrical power, for example, to an external system. In the motor
mode, an electric current is passed through the stator windings,
and the magnetic field produced by the current through the windings
32 interacts with the magnetic fields of the rotor 40 and the
stator 30. The interaction can cause rotation of the rotor 40.
Rotation of the rotor 40 can deliver mechanical power, for example,
via a shaft 172 at the drive end of the machine 100. Rotation of
the rotor 40 can also power a fluid compressor, for example, via
the shaft 170 at the non-drive end of the machine 100. In some
implementations, the electrical machine is operated at speeds
including greater than 3,600 rotations per minute.
[0019] During operation, either as a motor or as a generator,
various components in the electrical machine 100 produce heat
energy. For example, the windings 32 are made of a conducting
material. Example conducting materials include copper, aluminum,
silver, gold, and others. Due to the inherent resistivity of the
conducting material, current through the conducting material
produces heat during operation. Other components of the electrical
machine 100 can also produce heat during operation. For example,
friction between moving parts and electrical resistance in other
conductive components can also produce heat.
[0020] The electrical machine 100 includes a cooling system to cool
the various components of the machine 100. The cooling system
includes two cooling fluid sources 130a and 130b in fluid
communication with multiple cooling fluid conduits 180. Each
conduit 180 receives cooling fluid from either the source 130a or
the source 130b and communicates the fluid into a region of the
machine 100 inside the housing 20. The illustrated fluid source 130
is a motor-driven fan. Within the housing 20, the cooling fluid
receives heat energy from one or more components of the machine 100
via conductive heat transfer, while flowing adjacent the one or
more components. The cooling fluid then flows out of the housing
20, transporting the transferred heat energy away from the one or
more components, thus cooling the machine 100. Cooling fluid from
the source 130a is directed to the midstack region of the machine
100, at the axial center of the stator 30. The cooling fluid from
the source 130a cools the stator while flowing along the air gap 60
from the axial center of the stator 30 toward both ends of the
stator. Cooling fluid from the source 130b is directed onto the
exterior of both the drive and the non-drive ends of the machine to
cool the end turns 34.
[0021] Illustrated in FIG. 1A, a cooling fluid inlet 182a directs
cooling fluid from the conduit 180a into a volume about the end
turns 34a in the non-drive end of the machine 100, and a cooling
fluid inlet 182b directs cooling fluid from the conduit 180b into a
volume about the end turns 34b in the drive end of the machine 100.
Each of the volumes about the end turns 34a and 34b are defined in
the housing 20 by partitions 160 and 162. The partitions 160a and
162a define a volume about the non-drive end of the stator 30, and
the partitions 160b and 162b define a volume about the drive end of
the stator 30. The partitions 160 and 162 are implemented as
bulkheads with multiple ports and openings that allow the extension
of components and/or the flow of fluids through the partitions 160
and 162. The illustrated machine 100 is implemented without baffles
or shrouds to direct the flow through the volumes about each end of
the stator 30. However, in some implementations, such a baffle or
shroud can be included. outlets 184a and 184b are configured to
collect cooling fluid from the volume about the end turns 34a and
34b, respectively. From both outlets 184a and 184b, the cooling
fluid is directed into an exhaust manifold to a common exhaust
conduit 230 and exits the machine 100. Cooling fluid flowing along
the air gap 60 also enters the volumes about each end turn through
the air gap 60, which is radially inside of the interior lateral
surface of the stator 30. The cooling fluid from the air gap 60
also exits the machine 100 from the common exhaust conduit 230
(illustrated in FIG. 1B).
[0022] The fluid inlets 182 and the fluid outlets 184 both reside
radially outside of the interior lateral surface of the stator 30.
A pressure differential between the inlet 182a and the outlet 184a
can generate a flow of cooling fluid substantially transverse
across the exterior of the non-drive end of the stator. For
example, a flow of fluid between the inlet 182a and the outlet 184a
can function as a cooling flow dedicated to cooling the end turns
34a. Similarly, a flow of fluid between the inlet 182b and the
outlet 184b can function as a cooling flow dedicated to cooling the
end turns 34b. The inlet 182a and the outlet 184a can displace
cooling fluid outside of the stator 30 across an external diameter
of the non-drive end of the stator 30, cooling the end turns 34a.
Similarly, the inlet 182b and the outlet 184b can displace cooling
fluid outside of the stator 30 across an external diameter of the
drive end of the stator 30, cooling the end turns 34b.
[0023] Illustrated in FIG. 1B, a cooling fluid inlet 182c directs
cooling fluid from the conduit 180c into a volume in the midstack
of the machine 100, and a cooling fluid inlet 182d directs cooling
fluid from the conduit 180d into a volume in the midstack of the
machine 100. The inlets 182c and 182d direct cooling fluid from two
different azimuthal locations around the stator. Specifically, the
inlets 182c and 182d are diametrically opposed across a
cross-section near the axial center of the machine 100. A baffle
190 directs the cooling fluid circumferentially around the exterior
of the stator 30 from the inlets 182c and 182d. After circulating
circumferentially, the cooling fluid flows radially inward through
openings or ports in the baffle 190 into an annular manifold 80
formed circumferentially around the outer surface of the stator 30.
The stator 30 includes multiple substantially radial openings or
vents 70 providing communication between the annular manifold 80
and the air gap 60. The annular manifold 80 is implemented as a
midstack gap, which is a gap in the cooling jacket 210 and the
stator core at, or in some implementations near, the axial center
of the stator 30. The air gap 60 provides communication between the
vents 70 and the volume about the first and second ends of the
stator 30. For example, fluid may flow axially along the air gap
60, out of the drive end of the stator 30, and through the outlet
184b, and fluid may flow axially along the air gap 60, out of the
non-drive end of the stator 30, and through the outlet 184a.
[0024] The cooling system of the electrical machine 100 also
includes multiple liquid cooling jackets 210, illustrated in FIG.
1A. The liquid cooling jackets 210 extend around an exterior
circumference of the stator 30. The cooling jackets 210 are
configured to circulate liquid cooling fluid along serpentine flow
paths around the stator 30 to cool the stator 30. The serpentine
flow of cooling liquid is both circumferential and axial. That is
to say that the serpentine flow of cooling fluid, in aggregate, is
circumferential and includes axial traverses. Alternatively or in
addition, other flow path geometries can also be implemented in the
machine 100. The liquid cooling jackets 210 define a plurality of
separate circumferential flow paths 212. Each circumferential flow
path 212 can circulate liquid cooling fluid around a different
axial section of the stator 30 to cool the axial section of the
stator 30. The liquid cooling jackets 210 are part of a closed-loop
cooling system, wherein liquid cooling fluid is cyclically heated
and cooled as the fluid absorbs heat from the stator 30 and
transfers heat to a cooling source outside of the housing 20. In
some implementations, the liquid cooling jackets 210 are separable
from the housing 20 and separable from the stator 30. For example,
the liquid cooling jacket 210 can be removed from the electrical
machine 100 to be repaired or modified separately from the machine
100.
[0025] In one aspect of operation of the machine 100, cooling fluid
flows from the source 130a into the conduits 180a and 180b. The
fluid flows from the conduits 180a and 180b through the flow inlets
182a and 182b, respectively. From the flow inlets 182a and 182b,
the cooling fluid flows across the respective ends of the stator
and cools the respective end turns 34. After cooling the end turns
34, the cooling fluid flows through the respective outlets 184a and
184b into an exhaust manifold and out of the housing 20. Cooling
fluid also flows from the source 130b into the conduits 180c and
180d. The fluid flows from the conduits 180c and 180d through the
flow inlets 182c and 182d, respectively. From the flow inlets 182c
and 182d, the cooling fluid flows circumferentially through a
region in the housing around the exterior of the axial center of
the stator 30. Then the cooling fluid flows substantially radially
inward toward the rotor 40, through the manifold 80, through the
vents 70, and into the air gap 60. The cooling fluid then flows
axially along the gap 60. A portion of the fluid flows toward the
drive end of the machine 100, joining the flow of cooling fluid
across the end turns 34b and flowing into the exhaust manifold
through the outlet 184b. Another portion of the fluid flows toward
the non-drive end of the machine 100, joining the flow of cooling
fluid across the end turns 34a and flowing into the exhaust
manifold through the outlet 184a.
[0026] The electrical machine 200, illustrated in FIGS. 2A and 2B
includes an alternative embodiment of a cooling system. The machine
200 includes a single cooling fluid source 130 that directs cooling
fluid into a manifold 250. The manifold 250 distributes the cooling
fluid among various sections of the machine 200. The manifold 250
directs cooling fluid to the midstack of the machine 200 via
conduit 180g. The manifold 250 directs cooling fluid to both the
drive end and the non-drive end of the machine 200 via conduits
180f and 180e, respectively. The electrical machine 200 includes a
liquid cooling jacket 210 that has only two circumferential flow
paths 212.
[0027] In one aspect of operation of the machine 200, the rotor 40
rotates and drives a compressor component of the source 130.
Cooling fluid flows from the source 130 into the manifold 250. The
cooling is distributed in the manifold 250 among the conduits 180e,
180f, and 180g. From the conduits, the cooling fluid flows through
the respective flow inlets 182e, 182f, and 182g. From the flow
inlets 182e and 182f, the cooling fluid flows across the respective
ends of the stator and cools the end turns 34. After cooling the
end turns 34, the cooling fluid flows through the respective
outlets 184 into an exhaust manifold and out of the housing 20.
From the flow inlet 182g, the cooling fluid flows circumferentially
through a region in the housing around the exterior of the axial
center of the stator 30. Then the cooling fluid flows substantially
radially inward toward the rotor 40, through the manifold 80,
through the vents 70, and into the air gap 60. The cooling fluid
then flows axially along the gap 60. A portion of the fluid flows
toward each of the drive and non-drive ends of the machine 200,
joining the flow of cooling fluid across the end turns 34 and
flowing into the exhaust manifold through the outlets 184.
[0028] The illustrated electrical machines 100 and 200 are example
embodiments. Therefore, some implementations of an electrical
machine will include additional and/or different features with
respect to the illustrated examples, and some implementations of an
electrical machine will omit features of the illustrated
examples.
[0029] In FIG. 1A, the conductive windings 32 are incorporated into
the stator 30. However, in some implementations, the windings 32
are included in the rotor 40 rather than the stator 30. In FIG. 1A,
the shafts 170 and 172 are integrally formed to the rotor 40.
However, the shafts 170 and 172 may be separate elements directly
or indirectly attached to the rotor 40 and not integral to the
rotor 40. In FIG. 1A, partitions 160 and 162 define a volume about
each end of the stator 30. However, the machine 100 may be
implemented without one or more of the partitions 160 and 162. In
some implementations, the volume about each end of the stator 30 is
defined by the housing 20 and/or other features of the machine. In
some implementations, the volumes about the ends of the stator 30
are not defined by structure, but rather, by an air curtain, by a
pressure differential across the interior of the housing, or by the
relative orientation of the inlet 182 and the outlet 184.
[0030] In FIG. 1A, the inlets 182 are axially located at each end
of the stator 30, directing fluid substantially perpendicular to a
primary longitudinal axis defined by the rotor 40. In some
implementations, the inlets 182 are axially positioned radially
outside of the interior lateral surface of the stator and beyond
the ends of the stator 30 That is to say that, in some
implementations, a flow inlet or a flow inlet is located radially
outside of the stator and offset axially beyond an end of the
stator. For example, the inlet 182b may be located beyond the drive
end of the stator 30 and radially outside of the interior lateral
surface of the stator. In some implementations, the inlets 182
direct fluid at an angle with respect to the primary longitudinal
axis defined by the rotor 40. For example, the inlet 182b may
direct fluid at an angle toward or away from the axial center of
the stator 30. In FIG. 1A, both inlets 182a and 182b are at the
same azimuthal angle. That is to say that both inlets 182a and 182b
direct fluid at the same radial orientation across the stator
(i.e., from the top of the page). However, in some implementations,
one or both of the inlets 182a, 182b are offset at a different
azimuthal angle. For example, in some implementations, the inlets
182a and 182b may direct flow into the page, out of the page, or
from the bottom of the page.
[0031] In FIG. 1B, two flow inlets 182c and 182d are diametrically
opposed at the axial center of the stator 30. However, in some
implementations, one inlet 182 or more than two inlets 182 (e.g.,
three, four, five, or more) may be used to direct flow into the air
gap 60. Moreover, the inlets 182 may be at any azimuthal
orientation or set of azimuthal orientations around the stator 30,
and the inlets 182 may be at any axial position with respect to the
stator 30. For example, the inlets 182 directing flow into the air
gap 60 may be distributed between the partitions 162 at four
different azimuthal orientations.
[0032] The manifold 250 illustrated in FIGS. 2A and 2B, or a
similar structure, may also be used to distribute fluid in the
system 100. For example, the sources 130a and 130b may be in fluid
communication with a manifold that defines conduits that function
similarly to the conduits 180a, 180b, 180c, and 180d. Moreover, the
system 200 may be implemented without the manifold 250. For
example, each of the conduits 180e, 180f, and 180g may be defined
by separate pipes or conduits independent of the manifold 250.
[0033] In the illustrated implementations, the cooling sources 130
are motor-driven fans. However, the cooling sources may be any
fluid flow generator to provide a pressurized source of cooling
fluid. In some implementations, the cooling sources 130 are
compressors powered by rotation of the shaft 170. Examples of
cooling fluid include air, hydrogen, vapor, nitrogen, methane, and
any combination of these and/or other fluids. In some cases, the
cooling fluid is circulated for reasons other than to cool one or
more aspects of the machine. For example, in some cases, the
cooling fluid may be used to heat one or more components of the
machine. Example fluid flow generators include impellers, fans,
blowers, and others. A fluid flow generator may include a
centrifugal compressor, or any other type of compressor, uncoupled
from the shaft 170 and powered independently by an external system.
Furthermore, the fluid flow may cool various components and/or
parts of the electrical machine not explicitly named herein. For
example, the cooling fluid may cool various components of the rotor
40, the stator 30, the bearings 45, the housing 20, and other
components not explicitly named.
[0034] In some implementations, the flow of cooling fluid is
reversed. For example, cooling fluid can flow into the volumes
about the ends of the stator from the exhaust manifold through the
outlets 184. In this example, the cooling fluid flows from the
volume about the ends of the stator through the inlets 182 into the
conduits 180a, 180b and through the air gap 60 toward the conduits
180c, 180d. In some implementations, additional cooling fluid
guides may be added to direct or divert fluid. For example, in the
system 200, a baffle 190 directs fluid toward the sides of the
stator 30.
[0035] The liquid cooling jackets 210 are illustrated with four
circumferential flow paths 212, but one or more liquid cooling
jacket 210 can be implemented with any number of circumferential
flow paths 212. For example the liquid cooling jackets 210 may
include fewer or greater than four flow paths 212. The liquid
cooling jackets 210 can be implemented as an open- or closed-loop
cooling system. The liquid cooling jackets 210 can circulate liquid
cooling fluids such as water, nitrogen, and/or others.
[0036] In certain applications, the cooling system may be altered
to provide improved and/or optimal flow and/or cooling efficiency.
Features may be added in a centrifugal compressor intake, for
example, such as inlet guides or baffles, which may be manually or
automatically adjustable, or replaceable. Features may also be
added in some embodiments to adjust the flow path of the output of
the centrifugal impeller, including adjustable baffles, or throttle
valves. In some embodiments, the inlet air temperature,
composition, e.g., mixture of gases, or inlet pressure may be
adjusted to adjust the gas flow and/or heat transfer
characteristics.
[0037] In some embodiments, sensors may sense temperature
information, such as, for example, using RTDs (resistance
temperature detectors), thermocouples, or optical sensing devices,
and monitored at various locations, such as, for example, at the
rotor, stator, or the inlet and outlet to determine an inlet-outlet
differential, for input to a controller, such as a PLC
(programmable logic controller) or embedded processor device. The
controller may provide status indication or information,
communicate with other devices, for example, over a network, such
as a LAN or the Internet, or issue control commands to control
adjustment mechanisms, such as those capable of adjusting the flow
as described above. The controller may be part of a feedback
control system used to regulate one or more parameters, such as,
for example, monitored temperatures.
[0038] FIG. 3 is a flow chart illustrating an example process 300
for cooling an electrical machine. The process 300 can be used to
cool either of the example machines 100 and 200, as illustrated in
FIGS. 1 and 2. More generally, the process 300 can be used to cool
an electrical machine before, during, or after a generating,
motoring, or other mode of operation. In some implementations, the
process 300 includes more, fewer, or different operations in the
same or a different order.
[0039] At 302a, cooling fluid is received from a first flow inlet
into a corresponding volume about a first end of a stator. At 302b,
cooling fluid is received from a second flow inlet into a
corresponding volume about a second end of the stator. The first
flow inlet and/or the second flow inlet is located radially outside
of the interior surface of the stator. The first and second flow
inlets may be in fluid communication with the same cooling fluid
source or two different cooling fluid sources.
[0040] At 304a, cooling fluid is communicated substantially
transverse across the first end of the stator. At 304b, cooling
fluid is communicated substantially transverse across the second
end of the stator. At the first end of the stator and/or at the
second end of the stator, the substantially transverse flow
traverses an external transverse dimension of the stator without
entering the stator. For example, the substantially transverse flow
may flow across the stator from the top of the stator to the bottom
of the stator, or the substantially transverse flow may flow across
the stator from the left of the stator to the right of the stator,
or at any other angle. A substantially transverse flow of cooling
fluid may be a substantially non-axial flow, impinging an axial
cross-section of the stator substantially parallel to the diameter
of the cross-section. In some implementations, the substantially
transverse flow has an axial flow component. As the substantially
transverse flow impinges the exterior perimeter of the stator
and/or the exterior perimeter of the rotor, the flow is directed
around the circumference of the stator and/or the rotor, cooling
the stator and/or the rotor. The substantially transverse flow may
function as a cooling mechanism to cool the end turns. In some
implementations, the cooling fluid is simultaneously communicated
substantially transverse across both the first and second ends of
the stator. In other implementations, only the drive end or the
non-drive end of the stator is cooled by a substantially transverse
flow.
[0041] At 306, cooling fluid is received from a third flow inlet
into an air gap between the stator and the rotor. The third flow
inlet may be in fluid communication with the same or a different
source of cooling fluid as the first and/or second flow inlets. In
some implementations, the third flow inlet includes multiple flow
inlets distributed around the axial center of the stator at
different azimuthal locations. The cooling fluid from the third
flow inlet is communicated from into the air gap through a manifold
axially dividing a core of the stator.
[0042] At 308, cooling fluid is communicated axially along the air
gap into the volume about the first end and/or the second end of
the stator. In some implementations, the cooling fluid is
simultaneously communicated along the air gap in both axial
directions on either side of the third flow inlet. For example, if
the third flow inlet is located near the axial center of the
stator, the cooling fluid may simultaneously flow along the air gap
toward the drive end and toward the non-drive end of the electrical
machine from the center of the stator. In such a case, the cooling
fluid is communicated into the volume about the first end of the
stator and the volume about the second end of the stator. In other
cases, cooling fluid is communicated axially along the air gap to
only one end of the stator, for example, the drive end or the
non-drive end of the stator.
[0043] At 310a, cooling fluid is collected through a first flow
outlet from the volume about the first end of the stator. At 310b,
cooling fluid is collected through a second flow outlet from the
volume about the second end of the stator. The first flow outlet
and/or second flow outlet is located radially outside of the
interior surface of the stator. In some implementations, the
cooling fluid collected through the first flow outlet includes
cooling fluid from the first and third flow inlets. In some
implementations, the cooling fluid collected through the second
flow outlet includes cooling fluid from the second and third flow
inlets. From the first and second flow outlets, the cooling fluid
is communicated out of the machine through one or more exhaust
manifolds.
[0044] In some implementations, the first flow outlet and the first
flow inlet are cooperatively arranged to communicate the flow
substantially transverse across the first end of the stator, and/or
the second flow outlet and the second flow inlet are cooperatively
arranged to communicate the flow substantially transverse across
the second end of the stator. In some implementations, the first
flow outlet and the first flow inlet are arranged to displace
cooling fluid across an outer diameter of the first end of the
stator while the fluid is in the volume external to the stator
about the end turns, and/or the second flow outlet and the second
flow inlet are arranged to displace cooling fluid across an outer
diameter of the second end of the stator while the fluid is in the
volume external to the stator about the end turns.
[0045] A number of implementations have been described.
Nevertheless, it will be understood that various modifications may
be made. Accordingly, other implementations are within the scope of
the following claims.
* * * * *